Hello-new to the site and trying to diagnose what’s wrong with my lawn tractor. Bought a Kubota GR2010 with just over 600 hours and it bogs down when I drive up a hill or uneven terrain. If I’m going down a hill it’s running great with or without PTO. Up a hill or angled grade feels like it could stall with or without PTO. I replaced the fuel filter and the fuel pump assembly which attaches to head assembly and valve springs (figured it might’ve been the diaphragm pump gone bad). I’ve dumped plenty of fuel preservative, marvel mystery oil, etc., the past few weeks trying to get it right, and have only used 91 octane/ethanol free fuel. Any ideas or suggestion welcomed. Thanks again for reading.